Navigation device for displaying an approaching intersection

ABSTRACT

The present invention is adapted for use with a navigation device which performs 3 dimensional display on approaching an intersection. The navigation device of the present invention comprises a direction-of -travel detection means which detects a direction in which a vehicle is travelling, a direction-to-intersection detection means which calculates the difference between the direction in which a vehicle is travelling and a direction to an intersection position, a viewpoint direction calculation means which calculates a direction to a viewpoint in order to perform 3 dimensional display based on a difference between a detected direction in which a vehicle is travelling and a calculated direction, and a display means which performs display based on a calculated viewpoint direction. In this way, even when there is a large difference between direction in which the vehicle is travelling and the direction to the position of the intersection, it is possible to display the intersection.

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/JP98/02606 which has an Internationalfiling date of Jun. 12, 1998, which designated the United States ofAmerica.

FIELD OF THE INVENTION

The present invention relates to a navigation device which performs a 3dimensional display.

BACKGROUND OF THE INVENTION

FIG. 16 is a block diagram of a conventional navigation device. In thefigure, 110 is a CPU (central processing unit) which performs varioustypes of calculations. The CPU controls the vehicle position detectionmeans 110A which detects the vehicle position on the basis of signalsfrom a sensor or a GPS receiver, a route searching means 110B whichsearches a route to a destination from a detected vehicle position and adisplay conversion means 110C which converts route data read from aCD-ROM to bird's eye view data from a fixed viewpoint. 111 is a ROM(read on memory) which stores a program for various calculationsperformed by the CPU 110, 112 is a memory (DRAM) which storescalculation results and the like from the CPU 110 or data from a bearingsensor, distance sensor, GPS receiver, CDROM driver or the like. 113 isa backup memory (SRAM for preserving necessary data in the event of apower supply termination to the main device. 114 is a memory (Chinesecharacters, font ROM) which stores patterns such as signs or letters fordisplay on the crystal display. 115 is an image processor for forming adisplay image based on map data or the vehicle present position. 116 isa memory (VRAM) which composes map data output from the CPU 110, presentposition data and Chinese characters, town names output from the fontROM 114 and fonts and Chinese characters for road names or the like andstores images displayed on the crystal display. 117 is a RGB conversioncircuit for converting output data from the VRAM 116 to color data. Thecolor signals are output from the RGB conversion circuit 117 to thecrystal display. 118 is a communication interface.

The operation of the invention will be explained next.

FIG. 17 is a flowchart showing the operation of a conventionalnavigation device.

In a step ST1601, a display angle θx of the bird's eye view map whichdisplays the distance from the vehicle position to the intersection. Ina step ST1602, a bearing is determined from road network data read froma CD-ROM and the vehicle position. Conversion is performed to a bird'seye view map at the angle θx calculated in a step ST1601 and an enlargedscreen is prepared so that the direction of progress is in an upwarddirection. In a step ST1603, it is determined whether an intersectionhas been reached and in the event that the intersection has beenreached, the routine is terminated.

Steps ST1601, 1602, 1603 are repeated as shown in FIG. 17 until anintersection is reached from a current vehicle position. The angle θxapproaches 0 as the vehicle position approaches the intersection. Whenthe vehicle position is distant from the target intersection, theviewpoint is low, and as shown in FIG. 18(a), the display range is wide.However as the vehicle approaches the target intersection, the viewpointrises, and as shown in FIG. 18(b), the display range narrows to expressthe distance in an easily understandable form. Furthermore when thevehicle position has almost reached the intersection, the viewpoint isroughly above the target intersection and becomes a bird's eye view mapas shown in FIG. 18(c).

As the conventional navigation device is constructed as above, thedisplay range narrows as the intersection is reached. For example, whenthe difference between direction in which the vehicle is travelling andthe direction to the position of the intersection is great, the problemhas arisen that it has not been possible to display the intersection.

The present invention is proposed to solve the above problems and hasthe object of providing a navigation device which can display anintersection even when there is a great difference the direction inwhich the vehicle is travelling and the direction to the position of theintersection.

DISCLOSURE OF THE INVENTION

The navigation device of the present invention is a navigation devicewhich performs a 3 dimensional display when approaching an intersection.The navigation device comprises a direction of travel detection meanswhich detects the direction-of-travel of the vehicle, adirection-to-intersection detection means which calculates thedifference between the direction of travel of the vehicle and thedirection to the position of the intersection, a viewpoint directioncalculation means which detects the direction of the viewpoint in orderto perform 3 dimensional display based on the difference between adetected direction of vehicle travel and a calculated direction, and adisplay means which performs display based on a calculated viewpointdirection.

As a result of this arrangement, even when the difference between thedirection in which the vehicle is travelling and the direction to theposition of the intersection is great, it is possible display theintersection.

The navigation device of the present invention is a navigation devicewhich performs a 3 dimensional display when approaching an intersection.The navigation device comprises a vehicle position detection means whichdetects a vehicle position, an intersection distance calculation meanswhich calculates a distance from a detected vehicle position to anintersection, a viewpoint position calculation means which calculatesthe height of the viewpoint so that the height of the viewpoint for thepurposes of 3 dimensional display is reduced as the distance from thecalculated vehicle position to the intersection is reduced, and adisplay means which carries out a display based on the calculatedviewpoint height.

As a result of the above arrangement, it is possible to create a morerealistic appearance of approaching the intersection.

The navigation device according to the present invention is adapted toperform three dimensional display on approaching an intersection. Thenavigation device is provided with a traffic signal disposition meanswhich disposes a traffic signal at a position which is close to anactual position on an intersection when an intersection is determined toexist in a direction of vehicle travel, and a display means whichdisplays a traffic signal on a disposed position.

The navigation device of the present invention is a navigation devicewhich performs a 3 dimensional display when approaching an intersection.The device comprises a road existence determination means whichdetermines whether or not a road exists on the left side as seen fromthe direction in which the vehicle is travelling at the intersection, asignal mechanism disposal means which disposes a signal mechanism at aposition facing the direction of right turn in the road in the vicinityof the intersection when a road is determined to exist, and whichdisposes a signal mechanism at a position facing the direction of leftturn in the road in the direction in which the vehicle is travelling inthe vicinity of the intersection when a road is determined to not exist,and a display means which carries out a display which disposes a signalmechanism at a disposed position.

As a result of the arrangement above, it is possible to perform a 3dimensional display at the intersection in a realistic form.

The navigation device of the present invention is a navigation devicewhich performs a 3 dimensional display when approaching an intersection.It comprises a signal generation means which a right-hand or a left-handsignal at the intersection when the vehicle approaches an intersectionwhich turns left or right, a road width correction means which correctsa road width of roads crossing intersections other than the targetintersection when the vehicle approaches a right or left turningintersection, a display means which displays a generated signal on anintersection and which displays intersections other than the targetintersection with a corrected width.

By the above arrangement, it is possible to recognize a right or leftturning intersection without errors.

BRIEF EXPLANATION OF THE FIGURES

FIG. 1 is a block diagram of a navigation device according to a firstembodiment of the invention.

FIG. 2 is a flowchart showing the operation of a first embodiment of theinvention.

FIG. 3 explains the operation of a first embodiment of the invention.

FIG. 4 explains a result of a first embodiment of the present invention.

FIG. 5 shows a display example of a first embodiment of the presentinvention.

FIG. 6 is a block diagram of a navigation device according to a secondembodiment of the present invention.

FIG. 7 is a flowchart of the operation of a second embodiment of thepresent invention.

FIG. 8 shows the relationship between the angle of viewpoint and theinterval of the vehicle and the viewpoint and the distance of thevehicle position and the intersection according to a second embodimentof the present invention.

FIG. 9 shows the relationship between the height of the viewpoint andthe distance between the vehicle position and the intersection accordingto a second embodiment of the present invention.

FIG. 10 is a block diagram of a navigation device according to a thirdembodiment of the present invention.

FIG. 11 is a flowchart of the operation of a third embodiment of thepresent invention.

FIG. 12 explains the operation of a third embodiment of the presentinvention.

FIG. 13 is a block diagram of a navigation device according to a fourthembodiment of the present invention.

FIG. 14 is a flowchart of the operation of a fourth embodiment of thepresent invention.

FIG. 15 explains the operation of a fourth embodiment of the presentinvention.

FIG. 16 is a block diagram of a conventional navigation device.

FIG. 17 is a flowchart of the operation of a conventional navigationdevice.

FIG. 18 is a display example of a conventional navigation device.

PREFERRED EMBODIMENTS OF THE INVENTION

The preferred embodiments of the invention will be explained below indetail with reference to the accompanying figures.

Embodiment 1

FIG. 1 is a block diagram showing the layout of a navigation deviceaccording to a first embodiment of the present invention.

In FIG. 1, 1 is an input device such as keyboard or a pointing devicewhich inputs a destination, 2 is a storage device such as a data basewhich stores necessary information for searching and guiding the route,3 is a display device which such as a CRT or a crystal panel whichperforms display in order to guide the route and which functions as adisplay means, 4 is a calculation device which controls the abovedevices and which executes search and guide processing of the route.

The storage device 2 is provided with a data base 5 which stores mapdata necessary for the searching and guiding of a route.

The calculation device 4 comprises a 3 dimensional display means 6, adirection-of-travel detection means 7, a direction-to-intersectioncalculation means 8 and a viewpoint direction calculation means 9.

The 3 dimensional display means 6 performs 3 dimensional display whenthe vehicle approaches an intersection by the appropriate control of theheight of the viewpoint, the angle of viewpoint and the interval of thevehicle and the viewpoint in order to execute display. Thedirection-of-travel detection means 7 detects a direction in which thevehicle is travelling based on gyro-data or GPS data from a receiver notshown in the figure. The direction-to-intersection calculation means 8calculates the direction to the position of the intersection (theintersection direction) from the present position of the vehicle basedon map data and the detection results above. The viewpoint directioncalculation means 9 calculates a viewpoint direction (upper screendirection) for displaying the 3 dimensional image based on thedifference between the detected direction of travel of the vehicle andthe calculated direction.

The operation of the invention will now be explained.

FIG. 2 is a flowchart showing the operation of a first embodiment of theinvention.

In a calculation device 4, on approaching an intersection (step ST201),firstly a direction-of -travel detection means 7 detects a direction oftravel of a vehicle (step ST202) and a direction-tointersectioncalculation device 8 calculates a direction of travel of the vehicle andthe direction to the position of the intersection (step ST203). As shownin FIG. 3, the viewpoint direction calculation means 9 calculates aviewpoint direction θ3 for performing 3 dimensional display based ondetected intersection direction θ2 and the detected direction of vehicletravel θ1 (step ST204). The viewpoint direction θ3 is calculated forexample by the formula below.

θ3=(aθ1+bθ2)/(a+b)  (1)

In the above formula, a and b are constants and may be set for exampleas a=b=1.

As shown above, according to the first embodiment of the invention, when3 dimensional display is performed in the vicinity of an intersection,for example as shown in FIG. 4(a), when there is a large deviationbetween the position of the direction of travel {circle around (1)} andthe intersection direction {circle around (2)}, it is not possible todisplay the intersection. However in FIG. 4(b), since the direction ofthe viewpoint is set to a medial direction {circle around (3)} of, forexample, the direction of travel {circle around (1)} and theintersection direction {circle around (2)}, it becomes possible todisplay the intersection.

When the direction of the viewpoint is set to a medial direction of thedirection of travel and the intersection direction, efficient display ofthe road to the intersection is enabled on the screen.

For example, when a road to the intersection which turns greatly to theright-hand side in the direction of travel is displayed, the road canonly be displayed on the right-hand side of the screen when thedirection of the viewpoint is the direction of travel. Furthermore whenthe direction of the viewpoint is the direction to the intersection, theroad can only be displayed on the left-hand side of the screen. Incontrast, when the direction of the viewpoint is set to a medialdirection of the direction of travel and the intersection direction, theroad may be displayed on both sides of the screen and efficient displayof the road to the intersection is achieved.

Furthermore in the first embodiment, a, b which are the constants usedto calculate the direction of the viewpoint θ3 may be varied dependingon the degree of curve (curvature) of the road to the intersection. Thusit is possible to further vary the display of the road on the screen inan efficient manner.

Furthermore FIG. 5 shows an example of a display in accordance with thefirst embodiment of the present invention. The arrow in the figure showsthe direction in which the route is guided. Furthermore the guided routeis displayed on left vehicle lane of the road. The intersection which isindicated as turning left ahead is the target intersection. The presentposition mark in the figure is not displayed, however it is possible todisplay a present position mark on the arrow displayed on the screen.

Embodiment 2

FIG. 6 shows the layout of a navigation device according to a secondembodiment of the present invention. The same elements as in FIG. 1 aredesignated by similar reference numerals and will not be explained againhere. In this navigation device, a calculation device 4 comprises avehicle position detection means 51 which detects a vehicle position,and a intersection distance calculation means 52 which calculates thedistance of the detected vehicle position and the intersection.

The operation of the invention will now be explained.

FIG. 7 is a flowchart which shows the operation of a second embodimentof the invention.

In the calculation device 4, on approaching an intersection (stepST601), an intersection distance calculation means 52 calculates adistance between the vehicle position and an intersection (step ST602).The 3 dimensional display means 6 calculates the height of a viewpointso that the height of the viewpoint decreases in order to perform 3dimensional display the smaller the distance between the detectedvehicle position and the intersection becomes (step ST603). Below thisoperation is repeated until the intersection is passed.

When the height of the viewpoint in order to perform 3 dimensionaldisplay is taken to be h, the angle of the viewpoint φand the intervalof the vehicle and the viewpoint d, all the above are determined on thebasis of calculating by the distance L of the vehicle position and theintersection. For example, as shown in FIG. 8, the interval d (L) of theviewpoint and the vehicle and the angle of the viewpoint φ(L) increasesas the distance L of the vehicle position and the intersectiondecreases. The height h of the viewpoint increases as the distance Lbetween the vehicle position and the intersection decreases as shown inFIG. 9.

Apart from the distance to the intersection, it is possible to add otherconditions such as vehicle speed (for example the higher the vehiclespeed, the higher the viewpoint).

As shown above, according to the second embodiment of the invention,since the height of the viewpoint is reduced as the distance between thevehicle position and the intersection becomes smaller, it is possible tocreate a more realistic appearance of approaching the intersection.

Embodiment 3

FIG. 10 shows the layout of a navigation device according to a thirdembodiment of the present invention. The same elements as in FIG. 1 aredesignated by similar reference numerals and will not be explained againhere. In this navigation device, a calculation device 4 comprises a roadexistence determination means 91 which determines whether or not a roadexists on the left-hand side of the intersection in the direction inwhich the vehicle is travelling. A signal mechanism disposal means 92 isprovided which, when it is determined that a road exists, places asignal mechanism on a position facing the right turn direction of theroad in the vicinity of the intersection and which, when it isdetermined that a road does not exist, places a signal mechanism on aposition facing the left turn direction in the direction of vehicletravel in the vicinity of the intersection.

The operation of the invention will now be explained.

FIG. 11 is a flowchart showing the operation of a third embodiment ofthe present invention.

In a calculation device 4, as shown in FIG. 12(a), on approaching anintersection, a road existence determination means 91 determines whetheror not a road exists in the opposite direction {circle around (2)} tothe direction of travel {circle around (1)} (step ST1001). When a roaddoes not exist in the opposite direction {circle around (2)} to thedirection of travel {circle around (1)}, a virtual road (shown by thebroken line) is set with respect to {circle around (2)} (step ST1002).Next as shown in FIGS. 12 (b) and (c), the road existence determinationmeans 91 determines whether or not a road exists on the left-hand sidefrom the direction of travel of the vehicle at the intersection, that isto say, in the clockwise direction {circle around (3)} (step ST1003).The signal mechanism disposal means 92, as shown by FIG. 12 (b), placesa signal mechanism in a position {circle around (4)} facing the rightturning direction of the road in the proximity of the intersection whenit is determined that there is a road (step ST1004). If it is determinedthat there is no road, as shown in FIG. 12(c), a signal mechanism isplaced at a position {circle around (5)} facing the left turn directionof the road in the proximity of the intersection in the direction inwhich the vehicle is travelling (step ST1005).

As shown above, according to the third embodiment of the presentinvention, since a signal mechanism is displayed at a position actuallyclose to an intersection, it is possible to perform the realistic 3dimensional display of the intersection.

Embodiment 4

FIG. 13 is a block diagram showing a navigation device according to afourth embodiment of the present invention. The same elements as in FIG.1 are designated by similar reference numerals and will not be explainedagain here. In this navigation device, a calculation device 4 comprisesa signal generating device 121 which generates right-hand or left-handsignals at an intersection when a vehicle approaches an intersectionwhich turns left or right, and a road width correction means 122 whichcorrects a road width so that the transverse width of roads atintersections other than the target intersection is reduced when avehicle approaches an intersection which turns right or left.

The operation of the invention will now be explained.

FIG. 14 is a flowchart which shows the operation of a fourth embodimentof the present invention.

In a calculation device 4, when a vehicle approaches an intersectionwhich turns right or left (step ST1301), the signal generation means 121generates a right-hand or left-hand signal {circle around (1)} at theintersection as shown in FIG. 15(a) (step ST1302).

The width correction means 122, as shown in FIG. 15(b), corrects thewidth, for example by reducing it, so that the transverse width W2 of aroad at an intersection other than a target intersection is less thanthe width W1 of a road at the target intersection (step ST1303).Otherwise it is possible to widen the road width W1.

As shown above, according to the fourth embodiment, as shown in FIG.15(C), it is possible to recognize a right or left turning intersectionwithout errors since the intersecting roads in the intersection whichshould turn right or left are shown in a wider form than other roads.

The present embodiment was explained on the basis of an intersection,however, it is possible to vary the course to include three intersectingroads, four intersecting roads, branching roads, merging roads,multi-level crossings as the intersection and includes geographicalpoints of which it is necessary to draw the driver's attention to whiledriving.

Industrial Applicability

As shown above, the navigation device of the present inventionaccurately displays an intersection when approaching a targetedintersection for example by the motion of a vehicle. The displayrealistically creates the appearance of approaching the intersection andallows the recognition of right and left turning intersections withouterror. The present invention may be adapted to a three dimensionaldisplay.

What is claimed is:
 1. A navigation device which performs a threedimensional display on approaching an intersection comprising: adirection-of-travel detection means which detects the direction in whichthe vehicle is traveling, a direction-to-intersection calculation meanswhich calculates the direction to the position of the intersection, aviewpoint direction calculation means which calculates the direction ofthe viewpoint in order to perform the three dimensional display based ona weighted average of the direction of travel of a vehicle detected bythe direction-of-travel detection means and the direction calculated bythe direction-to-intersection calculation means, a display means whichperforms display based on the viewpoint direction calculated by theviewpoint direction calculation means.
 2. A navigation device accordingto claim 1 comprising: a traffic signal disposition means which disposesa traffic signal at a position which is close to an actual position onan intersection when an intersection is determined to exist in adirection of vehicle travel, and wherein said navigation device isadapted to display said traffic signal at a position disposed by saidtraffic signal disposition means.
 3. A navigation device according toclaim 2 comprising: a road existence determination means whichdetermines whether a road exists on a left side at an intersection fromthe direction in which the vehicle is travelling and a signal mechanismdisposal means which places a signal mechanism at a position facing aright turning direction of a road in the vicinity of an intersectionwhen a road is determined to exist by the road existence determinationmeans, and which places a signal mechanism at a position facing a leftturning direction of a road in the direction in which a vehicle istravelling in the vicinity of an intersection, when a road is determinednot to exist by the road existence determination means and wherein saidnavigation device performs display of a signal mechanism which is placedat a position by the signal mechanism disposition means.
 4. A navigationdevice according to claim 2 comprising: a road existence determinationmeans which determines whether a road exists on a left side at anintersection from the direction in which the vehicle is travelling, asignal mechanism disposal means which places a signal mechanism at aposition facing a right turning direction of a road in the vicinity ofan intersection when a road is determined to exist by the road existencedetermination means, and which places a signal mechanism at a positionfacing a left turning direction of a road in the direction in which avehicle is travelling in the vicinity of an intersection, when a road isdetermined not to exist by the road existence determination means andwherein said navigation device performs display of a signal mechanismwhich is placed at a position by the signal mechanism disposition means.5. A navigation device according to claim 1, comprising: a signgenerating means which generates a left or right turn signal at anintersection when a vehicle approaches a right turning or left turningintersection, and a road width correction means which corrects a roadwidth so that a width of a road crossing an intersection other than atarget intersection is less than that of a road width of a targetintersection and wherein a signal generated by the signal generatingmeans is displayed on an intersection and an intersection other than atarget intersection is displayed with a corrected road width by the roadwidth correction means.
 6. A navigation device which performs a threedimensional display on approaching an intersection comprising: a vehicleposition detection means which detects a vehicle position, intersectiondistance calculation means which calculates a distance from a vehicleposition detection by the vehicle position detection means to anintersection, viewpoint position calculation means which calculates theheight of a viewpoint so that the height of a viewpoint in order toperform three dimensional display decreases as the distance from avehicle position to an intersection detected by the intersectiondistance detection means decreases, a display mean s which carries outdisplay based on a viewpoint height calculated by the viewpoint positiondetection means, a signal generating means which generates a left orright turn signal at an intersection when a vehicle approaches a rightturning or left turning intersection, and a road width correction meanswhich corrects a road width so that a width of a road crossing anintersection other than a target intersection is less than that of aroad width of a target intersection and wherein a signal generated bythe signal generating means is displayed on an intersection and anintersection other than a target intersection is displayed with acorrected road width by the road width correction means.